Organofunctional group

Organofunctional silane Chemical structure of organofunctional group Functional groups used... 

When an organofunctional group replaces a methyl group on a siloxy unit, a superscript is used to describe the unit. The most common groups that are encountered can be symbolized as alkyl (R), hydrogen (H), phenyl (Ph), hydroxyl (OH), trifluoropropyl (F), and vinyl (Vi). Thus, vinyl-endblocked-PDMS is represented by (Scheme 3), and a trimethylsiloxy-... 

The organofunctional group (R) in the coupling agent causes the reaction with the polymer. This could be a copolymerization and/or the formation of an interpenetrating network. This curing reaction of a silane-treated substrate enhances the wetting by the resin (Table 9). 

Organofunctional group Chemical structure OSi-Specialties Germany GmbH product Critical surface tension of glass with silane treatment [dyne/cm] Applied polymers (abbreviations according ASTM 1600)... 

Trade name Organofunctional group Chemical structure... 

All of these reactions have been used to bind organofunctional groups to inorganic surfaces for chromatographic purposes (18, 48, 61, 68, 69). A totally different approach to the use of silica as the support is illustrated in the following reaction in which the functional group, for example, a tertiary phosphine, is built into the trialkoxysilane which is then polymerized to produce a nonlinear polymer based on an —Si—O—Si— backbone (115) ... 

Organofunctional group Chemical structure Dow Coming designation... 

A critical concern in the use of organofunctional silanes is the effects that the organofunctional groups and the silane ester groups have on the hydrolysis reactions occurring at silicon. 

Silane coupling agents the role of the organofunctional group... 

Silane coupling agents have the structure R—Si—X3, where R represents an organofunctional group and X is generally alkoxy. They are generally applied from water solutions or from organic solvent-water mixtures. In the presence of water, hydrolysis occurs step-wise to form alkoxysilanols, and eventually silane triols. Condensation of the silanols to siloxanes also occurs. Reactions shown schematically below ... 

The examples summarized above are but indicative of the increasing body of evidence in support of the chemical bonding theory, and of the role of the silane organofunctional group in the formation of covalent bonds at the coupling agent/ matrix interphase by reaction or by co-polymerization with the formation of an interpenetrating polymer network. 

As in previous years the major method used for attaching an organofunctional group to a siloxane backbone is hydrosilylation. Even in this much studied field there is still the potential for surprising and potentially very useful results. Thus, Crivello and Bi... 

The introduction of organofunctional groups, i.e. the use of alkoxysilanes of the type (R O Si—X—A, where A is a functional organic group and X is a chemically inert spacer permanently linking Si and A, results in a more extensive chemical modification of the materials76. The properties of the organic functions A supplement the properties of the polysiloxane matrix formed by hydrolysis and condensation of the Si(OR )3 and Si(OR )4 units. 

The incorporation of organofunctional groups on the silica surface may be effectuated during the synthesis of the silica material. The addition of organofunctional alkoxysilanes to the TEOS solution in the sol-gel process, produces functionalized silica gels. This procedure does not allow a careful control of the obtained surface morphology. Since the relative amounts of silane and TEOS is the only variable parameter, neither layer thickness, nor modification density can be precisely tuned. This results in an irreproducible functionalization of the surface. 

Y = organofunctional group OX = silicon-functional group n = typically 0 or 3... 

The organofunctional group Y links with the polymer. This group must be chosen carefully to ensure maximum compatibility with the resin. The silicon-functional groups OX, usually alkoxy groups, must be hydrolyzed to the silanol (Si-OH) first before they can bond to the substrate or crosslink. 

Alkoxysilanes, including tetraalkoxysilanes, are utilized as crosslinking components in silicone rubbers, in the manufacture of silicone resins, as adhesion promoters with special organofunctional groups e.g. glass fiber layers, in the formulation of corrosion-resistant paints and in mold construction. 

Wade, R. C. Catalyzed reductions of organofunctional groups with sodium borohydride. J. Mol. Catal. 1983,18, 273-297. 

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